It would be best for the celebrant at Mass to change sides on the altar immediately after he finishes his homily at the pulpit.

Instead of going back to the side of the altar where he faces the people, the priest could go to the side of the altar where his back is to the people and he faces (East) (the Apse) (the large crucifix on the rear wall) and there begin the preparation of the gifts. The priest would remain on that side of the altar until the end of the Mass.